1. Field of the Invention
The present invention relates to a semiconductor device. More specifically, the invention relates to a semiconductor device having a package structure in which a semiconductor chip with a plurality of pads along one side thereof is mounted on a lead frame and sealed with resin or the like (referred to as a packaged semiconductor device hereinafter).
2. Description of the Related Art
A packaged semiconductor device having a ball grid array (BGA) structure in which a plurality of pads are all arranged along one side of a semiconductor chip, has recently been developed (Jpn. Pat. Appln. KOKAI Publication No. 2001-102515, pages 4 and 5 and FIG. 1, for example). In the packaged semiconductor device, the semiconductor chip is stacked on and displaced from a low-level chip, thereby reducing the size of the semiconductor chip and facilitating wire bonding.
If, however, a semiconductor chip with a plurality of pads along one side thereof is applied to a packaged semiconductor device having a thin small outline package (TSOP) structure, the following problem occurs. In this packaged semiconductor device, the semiconductor chip is fixed on a die pad section of a lead frame by an insulative adhesive, and the pads on the chip are connected to the internal leads of the lead frame by bonding wires, respectively. Some of the internal leads are arranged close to the pads, whereas the others are arranged away from the pads. In order to connect the latter internal leads to the pads, very long bonding wires are required. In the subsequent resin-sealing process, the long bonding wires are easily dropped due to resin, and adjacent bonding wires are easily brought into contact with each other (electrically short-circuited).
Jpn. Pat. Appln. KOKAI Publication No. 2001-217383 discloses a semiconductor device in which a semiconductor chip with a plurality of bonding pads along one side of the main surface thereof and another semiconductor chip of the same type are stacked on the substrate and thus the bonding pads of these chips are close to each other.